CN110071260B - Nonaqueous electrolyte secondary battery - Google Patents

Nonaqueous electrolyte secondary battery Download PDF

Info

Publication number
CN110071260B
CN110071260B CN201910054594.7A CN201910054594A CN110071260B CN 110071260 B CN110071260 B CN 110071260B CN 201910054594 A CN201910054594 A CN 201910054594A CN 110071260 B CN110071260 B CN 110071260B
Authority
CN
China
Prior art keywords
protective layer
resin
mass
positive electrode
less
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN201910054594.7A
Other languages
Chinese (zh)
Other versions
CN110071260A (en
Inventor
部田浩司
岛村治成
福本友祐
落合章浩
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Toyota Motor Corp
Original Assignee
Toyota Motor Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Toyota Motor Corp filed Critical Toyota Motor Corp
Publication of CN110071260A publication Critical patent/CN110071260A/en
Application granted granted Critical
Publication of CN110071260B publication Critical patent/CN110071260B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • H01M10/0587—Construction or manufacture of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/665—Composites
    • H01M4/667—Composites in the form of layers, e.g. coatings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/668—Composites of electroconductive material and synthetic resins
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/64—Carriers or collectors
    • H01M4/70—Carriers or collectors characterised by shape or form
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Composite Materials (AREA)
  • Inorganic Chemistry (AREA)
  • Secondary Cells (AREA)
  • Battery Electrode And Active Subsutance (AREA)
  • Cell Electrode Carriers And Collectors (AREA)

Abstract

A nonaqueous electrolyte secondary battery includes at least a positive electrode, a negative electrode, a separator, and a nonaqueous electrolyte. The positive electrode includes a positive electrode current collector, a protective layer, and a positive electrode mixture layer. The protective layer is disposed between the positive electrode current collector and the positive electrode mixture layer. The protective layer includes at least a1 st protective layer and a2 nd protective layer. The 1 st protective layer is disposed on the surface of the positive electrode current collector. The 1 st protective layer includes a1 st conductive material and a1 st resin. The 1 st resin is a non-thermoplastic polyimide resin. The 2 nd protective layer is disposed on the surface of the 1 st protective layer. The 2 nd protective layer contains at least a2 nd conductive material and a resin a. The resin a is a thermoplastic resin. The melting point of resin A is lower than the thermal decomposition temperature of the 1 st resin. The expansion coefficient of the resin A is larger than that of the 1 st resin.

Description

Nonaqueous electrolyte secondary battery
Technical Field
The present disclosure relates to a nonaqueous electrolyte secondary battery.
Background
International publication No. 2012/005301 discloses an electrode body in which an undercoat layer (protective layer) is disposed between a positive electrode current collector and a positive electrode material mixture layer. The protective layer includes an organic binder and a conductive material. It is considered that the organic binder and the conductive material are evaporated or decomposed when heated at a predetermined temperature or higher.
Disclosure of Invention
As described above, it is considered that the protective layer is formed between the positive electrode mixture layer and the positive electrode current collector. By forming this protective layer, it is expected that the temperature rise of the battery is suppressed at the time of abnormality such as nail penetration.
The protective layer disclosed in international publication No. 2012/005301, comprises an organic binder and a conductive material. It is considered that the thermal expansion rates of the organic binder and the conductive material are largely different. Therefore, when the nail penetration occurs, voids (cracks) may be generated in the protective layer due to the difference in thermal expansion coefficient. If the voids are enlarged, the protective layer may be peeled off from the positive electrode current collector, and the nail may come into contact with the positive electrode current collector. As a result, there is a possibility that the increase in the battery temperature cannot be sufficiently suppressed.
The purpose of the present disclosure is to provide a nonaqueous electrolyte secondary battery in which a rise in battery temperature during nailing is suppressed.
The technical configuration and operational effects of the present disclosure will be described below. However, the mechanism of action of the present disclosure encompasses presumption. The scope of the claims should not be limited by the correctness of the mechanism of action.
[1] A nonaqueous electrolyte secondary battery includes at least a positive electrode, a negative electrode, a separator, and a nonaqueous electrolyte. The positive electrode includes a positive electrode current collector, a protective layer, and a positive electrode mixture layer. The protective layer is disposed between the positive electrode current collector and the positive electrode mixture layer. The protective layer includes at least a1 st protective layer and a2 nd protective layer. The 1 st protective layer is disposed on the surface of the positive electrode current collector. The 1 st protective layer includes a1 st conductive material and a1 st resin. The 1 st resin is a non-thermoplastic polyimide resin. The 2 nd protective layer is disposed on the surface of the 1 st protective layer. The 2 nd protective layer contains at least a2 nd conductive material and a resin a. The resin a is a thermoplastic resin. The melting point of resin A is lower than the thermal decomposition temperature of the 1 st resin. The expansion coefficient of the resin A is larger than that of the 1 st resin.
Fig. 1 is a1 st sectional conceptual view for explaining an action mechanism of the present disclosure.
Fig. 1 shows a thickness-direction cross section of a part of the positive electrode. A protective layer 10 is shown in fig. 1. The positive electrode includes a positive electrode current collector 101, a protective layer 10, and a positive electrode mixture layer 102. The protective layer 10 is disposed between the positive electrode current collector 101 and the positive electrode mixture layer 102. The protective layer 10 includes at least a1 st protective layer 11 and a2 nd protective layer 12. The 1 st protective layer 11 is disposed on the surface of the positive electrode current collector 101. The 1 st protective layer 11 contains a1 st conductive material and a1 st resin. The 1 st resin is a non-thermoplastic polyimide resin. The 2 nd passivation layer 12 is disposed on the surface of the 1 st passivation layer 11. The 2 nd protective layer 12 contains at least the 2 nd conductive material and the resin a. The resin a is a thermoplastic resin.
Generally, when the nail penetration occurs, the positive electrode and the negative electrode are short-circuited at a low resistance by the nail as a low resistance body, and a large amount of joule heat is generated. Due to the joule heat, the separator around the nail melts, the positive electrode mixture layer and the negative electrode mixture layer contact each other, and a larger short-circuit current continues to flow to generate heat, which leads to thermal runaway (thermal runaway). In addition, not only a short circuit occurs via the nail, but also a short circuit occurs when the positive electrode (negative electrode) current collector and the negative electrode (positive electrode) mixture layer are in direct contact, resulting in further thermal runaway.
When a nail penetrates the nonaqueous electrolyte secondary battery (hereinafter also simply referred to as "battery") according to the present disclosure, the following phenomena (1) to (4) are considered to be able to occur. These phenomena interact with each other, and it is expected that the temperature rise of the battery at the time of nailing will be suppressed.
(1) A short circuit occurs in a part of the battery due to penetration of the nail into the battery, and the temperature locally rises in the battery due to joule heat.
(2) The expansion coefficient of the resin a contained in the 2 nd protective layer 12 is larger than that of the 1 st resin contained in the 1 st protective layer 11. Therefore, it is considered that the 2 nd protective layer 12 including the resin a expands to cover the 1 st protective layer 11 with an increase in temperature of the battery. This can prevent the 1 st protective layer 11 and the 2 nd protective layer 12 from being peeled off by the nail penetration.
(3) The melting point of the resin a contained in the 2 nd protective layer 12 is lower than the thermal decomposition temperature of the 1 st resin contained in the 1 st protective layer 11. It is considered that the resin a melts into a liquid state as the temperature of the battery increases. Therefore, when the 1 st resist layer 11 has a void, it is considered that the liquid resin a contained in the 2 nd resist layer 12 enters the void and is welded. This can prevent the first protective layer 11 from peeling off from the positive electrode current collector 101 due to the void and the positive electrode current collector 101 from being exposed.
(4) It is considered that the resin a melted and liquefied adheres to the outer surface of the nail. This can suppress a decrease in short-circuit resistance during nailing, and can suppress an increase in battery temperature during nailing.
[2] The resin a may be at least 1 selected from polyvinylidene fluoride (PVDF), polyethylene, polycarbonate, silicone rubber, polyethylene terephthalate (PET), fluororubber, and Polytetrafluoroethylene (PTFE). These resins have low melting points and large expansion coefficients, and therefore, it is expected that the increase in battery temperature at the time of nail penetration can be significantly suppressed.
[3] The 2 nd protective layer may further include a2 nd resin. The 2 nd resin is a non-thermoplastic polyimide resin. It is considered that the 2 nd protective layer is thermally stable by the 2 nd protective layer further containing the 2 nd resin (non-thermoplastic polyimide resin). This can be expected to provide a thermally stable battery.
[4] The protective layer may further comprise a3 rd protective layer. The 3 rd protection layer is disposed on the surface of the 2 nd protection layer. The 3 rd protective layer has the same composition and thickness as the 1 st protective layer. That is, the 1 st protective layer is disposed on the surface of the 2 nd protective layer as the 3 rd protective layer. By disposing the 3 rd protective layer (i.e., the 1 st protective layer) on the surface of the 2 nd protective layer, a more thermally stable battery can be expected.
[5] In the battery having the structure of [1] or [2], the content of the 1 st conductive material with respect to the 1 st protective layer may be 0.5% by mass or more and 50% by mass or less, the content of the 2 nd conductive material with respect to the 2 nd protective layer may be 5% by mass or more and 50% by mass or less, and the content of the resin a with respect to the 2 nd protective layer may be 50% by mass or more and 95% by mass or less. The 1 st protective layer and the 2 nd protective layer may have a thickness of 0.1 μm or more and 10 μm or less, respectively. By including this structure, a battery in which an increase in battery temperature during nailing is suppressed and an increase in battery resistance during high-load charging and discharging is suppressed can be expected.
[6] In the battery having the structure of [3] or [4], the content of the 1 st conductive material with respect to the 1 st protective layer may be 0.5% by mass or more and 50% by mass or less, the content of the 2 nd conductive material with respect to the 2 nd protective layer may be 0.5% by mass or more and 50% by mass or less, and the content of the resin a with respect to the 2 nd protective layer may be 0.1% by mass or more and 30% by mass or less. The 1 st protective layer and the 2 nd protective layer may have a thickness of 0.1 μm or more and 10 μm or less, respectively. By including this structure, a battery in which an increase in battery temperature during nailing is suppressed and an increase in battery resistance during high-load charging and discharging is suppressed can be expected.
[ 7 ] the difference (. beta. - α) between the thermal decomposition temperature α of the 1 st resin and the melting point β of the positive electrode current collector may be 120 ℃ or lower. It is considered that when the difference (β - α) between the thermal decomposition temperature α of the 1 st resin and the melting point β of the positive electrode current collector is 120 ℃ or less, the time from the start of thermal decomposition of the 1 st resin to the fusing of the positive electrode current collector becomes short. This can shorten the time for exposing the positive electrode current collector, and reduce the frequency of contact between the positive electrode current collector and the nail. As a result, it is expected that the decrease in short-circuit resistance at the time of nailing is suppressed, and the increase in battery temperature at the time of nailing is remarkably suppressed.
The above and other objects, features, aspects and advantages of the present invention will become apparent from the following detailed description of the present invention, which is to be read in connection with the accompanying drawings.
Drawings
Fig. 1 is a1 st sectional conceptual view for explaining an action mechanism of the present disclosure.
Fig. 2 is a conceptual sectional view 2 showing a part of the structure of the positive electrode of the present embodiment.
Fig. 3 is a schematic diagram showing an example of the structure of the nonaqueous electrolyte secondary battery of the present embodiment.
Fig. 4 is a schematic diagram showing an example of the structure of the electrode group according to the present embodiment.
Fig. 5 is a schematic diagram showing an example of the structure of the positive electrode of the present embodiment.
Fig. 6 is a schematic diagram showing an example of the structure of the negative electrode of the present embodiment.
Detailed Description
Hereinafter, embodiments of the present disclosure (referred to as "the present embodiments" in the present specification) will be described. However, the following description does not limit the scope of the claims.
Hereinafter, a lithium ion secondary battery will be described as an example. However, the nonaqueous electrolyte secondary battery of the present embodiment should not be limited to a lithium ion secondary battery. The nonaqueous electrolyte secondary battery of the present embodiment may be, for example, a sodium ion secondary battery, a lithium metal secondary battery, or the like.
Hereinafter, a nonaqueous electrolyte secondary battery (lithium ion secondary battery) in which the protective layer 10 is disposed between the positive electrode current collector 101 and the positive electrode mixture layer 102 will be described. The protective layer 10 may be disposed between the negative electrode current collector 201 and the negative electrode mixture layer 202 in addition to between the positive electrode current collector 101 and the positive electrode mixture layer 102.
< nonaqueous electrolyte Secondary Battery >
Fig. 3 is a schematic diagram showing an example of the structure of the nonaqueous electrolyte secondary battery of the present embodiment.
The outer shape of the battery 1000 is square. That is, the battery 1000 is a prismatic battery. However, the battery of the present embodiment should not be limited to the rectangular battery. The battery of the present embodiment may be, for example, a cylindrical battery. Although not shown in fig. 3, the battery 1000 includes at least a positive electrode, a negative electrode, a separator, and a nonaqueous electrolyte.
Shell body
Battery 1000 includes a housing 1001. The housing 1001 is sealed. The case 1001 may be made of, for example, an aluminum (Al) alloy or the like. However, as long as the case 1001 can be sealed, the case may be, for example, a bag (pouch) made of an Al laminated film. That is, the battery of the present embodiment may be a laminate type battery.
The housing 1001 includes a container 1002 and a lid 1003. The cover 1003 is joined to the container 1002 by, for example, laser welding. A positive electrode terminal 901 and a negative electrode terminal 902 are provided on the lid 1003. The lid 1003 may further include a liquid inlet, a gas discharge valve, a current interruption mechanism (none of which are shown), and the like.
Electrode group
Fig. 4 is a schematic diagram showing an example of the structure of the electrode group according to the present embodiment.
The electrode group 500 is of a wound type. That is, the positive electrode 100, the separator 300, the negative electrode 200, and the separator 300 are stacked in this order, and are wound in a spiral shape, thereby forming the electrode group 500. However, the electrode group of the present embodiment is not limited to the wound type. The electrode group of the present embodiment may be a stacked (stack) type. The stacked electrode group can be formed, for example, by alternately stacking the positive electrodes 100 and the negative electrodes 200 with the separators 300 interposed between the positive electrodes 100 and the negative electrodes 200.
Positive electrode
Fig. 5 is a schematic diagram showing an example of the structure of the positive electrode of the present embodiment.
The battery 1000 includes at least the positive electrode 100. The positive electrode 100 may be a strip-shaped sheet. The positive electrode 100 includes a positive electrode mixture layer 102 and a positive electrode current collector 101. Although not shown in fig. 5, the protective layer 10 is disposed between the positive electrode current collector 101 and the positive electrode mixture layer 102 (fig. 1). That is, the positive electrode 100 includes a positive electrode current collector 101, a protective layer 10 (fig. 1), and a positive electrode mixture layer 102.
(Positive electrode collector)
The positive electrode current collector 101 is an electrode substrate having conductivity. The positive electrode current collector 101 may have a thickness of, for example, 9 μm or more and 17 μm or less. The positive electrode current collector 101 may be, for example, a pure Al foil, an Al alloy foil, or the like.
(Positive electrode mixture layer)
The positive electrode mixture layer 102 is formed on the surface of the protective layer 10 (fig. 1). The positive electrode mixture layer 102 may have a thickness of, for example, 100 μm or more and 200 μm or less. The positive electrode mixture layer 102 contains at least a positive electrode active material. The positive electrode mixture layer 102 may contain, for example, 80 mass% to 98 mass% of a positive electrode active material, 1 mass% to 10 mass% of a conductive material, and 1 mass% to 10 mass% of a binder.
The positive electrode active material is not particularly limited. The positive electrode active material may be, for example, LiCoO2、LiNiO2、LiMnO2、LiMn2O4、LiNi1/3Co1/3Mn1/3O2、LiNi0.82Co0.15Mn0.03O2、LiFePO4And the like. 1 kind of positive electrode active material can be used alone. Two or more kinds of positive electrode active materials may be used in combination. The conductive material and the binder are not particularly limited. The conductive material may be, for example, Acetylene Black (AB), furnace black, Vapor Grown Carbon Fiber (VGCF), graphite, or the like. BondingThe agent may be, for example, polyvinylidene fluoride (PVdF), Styrene Butadiene Rubber (SBR), Polytetrafluoroethylene (PTFE), or the like.
The positive electrode active material may have D50 of, for example, 1 μm or more and 30 μm or less. In the present specification, "D50" represents a particle diameter in which the cumulative particle volume from the fine particle side in a volume-based particle diameter distribution obtained by the laser diffraction scattering method is 50% of the total particle volume.
Protective layer
As shown in fig. 1, the protective layer 10 is disposed between the positive electrode current collector 101 and the positive electrode mixture layer 102. The protective layer 10 includes at least a1 st protective layer 11 and a2 nd protective layer 12.
1 st protective layer
The 1 st protective layer 11 is disposed on the surface of the positive electrode current collector 101. The 1 st protective layer 11 may be disposed on both the front and back surfaces of the positive electrode current collector 101. The 1 st protective layer 11 contains a1 st conductive material and a1 st resin. The 1 st protective layer 11 may have a thickness of, for example, 0.1 μm or more and 15 μm or less, and preferably has a thickness of 0.1 μm or more and 10 μm or less. If the thickness of the 1 st protective layer 11 is less than 0.1 μm, the 1 st protective layer 11 tends to be difficult to form. If the thickness of the 1 st protective layer 11 exceeds 15 μm, the battery resistance may increase during high-load charge and discharge.
(the 1 st conductive material)
The 1 st conductive material may be, for example, Acetylene Black (AB), furnace black, Vapor Grown Carbon Fiber (VGCF), artificial graphite, or the like. These conductive materials may be used alone in 1 kind, or two or more kinds may be used in combination.
The content of the 1 st conductive material with respect to the 1 st protective layer 11 may be 0.2 mass% or more and 60 mass% or less, and preferably the content thereof with respect to the 1 st protective layer 11 is 0.5 mass% or more and 50 mass% or less. When the content of the 1 st conductive material in the 1 st protective layer 11 is 0.5 mass% or more and 50 mass% or less, a battery in which an increase in battery temperature during nail penetration is suppressed and an increase in battery resistance during high-load charge and discharge is suppressed can be expected.
(the 1 st resin)
The 1 st resin is a non-thermoplastic polyimide resin. In the present specification, "non-thermoplastic resin" means a resin having a property of not melt-flowing at a temperature of less than 200 ℃. In the present specification, the term "non-thermoplastic polyimide resin" refers to a polymer having an imide group in a repeating unit constituting a main chain and having a thermal decomposition temperature of at least 500 ℃. The "non-thermoplastic polyimide resin" is not particularly limited as long as the properties of the polyimide resin satisfy the thermal decomposition temperature. The difference (β - α) between the thermal decomposition temperature α of the 1 st resin and the melting point β of the positive electrode current collector 101 is preferably 120 ℃ or less. For example, when the positive electrode current collector 101 is an aluminum foil, the melting point β of the positive electrode current collector 101 is considered to be about 660 ℃. In this case, the thermal decomposition temperature α of the 1 st resin is preferably 540 ℃ or higher.
In the present specification, the "thermal decomposition temperature of the 1 st resin" means a temperature at which weight reduction starts due to thermal decomposition of the 1 st resin. The thermal decomposition temperature can be measured by thermogravimetry-differential calorimetry (TG-DTA: thermal gradient-differential thermal analysis). Specific measurement conditions include, for example, a condition in which the temperature is raised at a rate of 5 ℃/min. The "thermal decomposition temperature of the 1 st resin" can be measured by using an endothermic peak accompanying thermal decomposition.
As a method for synthesizing a polyimide resin having the above characteristics, for example, a precursor (polyamic acid) may be subjected to heat treatment. That is, the polyimide resin may be a polyimide resin derived from a polyamic acid. As the polyamic acid, for example, a polyamic acid synthesized from a composition containing a tetracarboxylic anhydride and a diamine can be used. Typical examples of the method for synthesizing the polyimide resin include the following methods: polyamic acid obtained by polymerizing pyromellitic acid dihydrate and 4, 4' -diaminodiphenyl ether is imidized by heat treatment as shown in the following reaction formula.
Figure GDA0003251459670000081
The thermal expansion coefficient of the 1 st resin is smaller than that of the resin A. The thermal expansion coefficient of the 1 st resin may be, for example, 10 ppm/DEG C or more and 60 ppm/DEG C or less. The thermal expansion coefficient of the 1 st resin can be measured according to, for example, JIS K7197 "method for testing linear expansion coefficient based on thermal mechanical analysis of plastics".
The 2 nd protective layer
The 2 nd passivation layer 12 is disposed on the surface of the 1 st passivation layer 11. The 2 nd protective layer 12 contains at least the 2 nd conductive material and the resin a. The 2 nd protective layer 12 may have a thickness of, for example, 0.1 μm or more and 15 μm or less, and preferably has a thickness of 0.1 μm or more and 10 μm or less. If the thickness of the 2 nd protective layer 12 is less than 0.1 μm, the 2 nd protective layer 12 tends to be difficult to form. If the thickness of the 2 nd protective layer 12 exceeds 15 μm, the battery resistance during high-load charge and discharge may increase.
(No. 2 conductive Material)
As the 2 nd conductive material, the same conductive material as the 1 st conductive material can be used. That is, Acetylene Black (AB), furnace black, Vapor Grown Carbon Fiber (VGCF), artificial graphite, or the like may be used. These conductive materials may be used alone in 1 kind, or two or more kinds may be used in combination.
The 2 nd conductive material may be contained in the 2 nd protective layer 12 as described below in each case. (1) The case where the 2 nd protective layer 12 is composed of the 2 nd conductive material and the resin a; (2) the 2 nd protective layer 12 contains a2 nd resin described later in addition to the 2 nd conductive material and the resin a; and (3) the case where the protective layer 10 includes a3 rd protective layer described later.
In the case of (1) above, the content of the 2 nd conductive material with respect to the 2 nd protective layer 12 may be 2 mass% or more and 55 mass% or less, and preferably 5 mass% or more and 50 mass% or less.
In the case of (2) above, the content of the 2 nd conductive material with respect to the 2 nd protective layer 12 may be 0.4% by mass or more and 60% by mass or less, and preferably 0.5% by mass or more and 50% by mass or less.
In the case of (3) above, the content of the 2 nd conductive material with respect to the 2 nd protective layer 12 may be 0.4% by mass or more and 60% by mass or less, and preferably 0.5% by mass or more and 50% by mass or less.
(resin A)
The resin A is a thermoplastic resin. The resin a is preferably at least one selected from the group consisting of polyvinylidene fluoride (PVDF), polyethylene, polycarbonate, silicone rubber, polyethylene terephthalate, fluororubber, and Polytetrafluoroethylene (PTFE). That is, these resins may be used alone in 1 kind, or 2 or more kinds may be used in combination.
The melting point of resin A is lower than the thermal decomposition temperature of the 1 st resin. The melting point of the resin a may be, for example, 165 ℃ to 327 ℃. As the resin a, resins other than the above may be used as long as the melting point is lower than the thermal decomposition temperature of the 1 st resin. In the present specification, the "melting point of resin a" can be measured by thermogravimetry-differential calorimetry (TG-DTA) analysis. Specific measurement conditions include, for example, a condition in which the temperature is raised at a rate of 5 ℃/min. The "melting point of resin a" can be defined by the endothermic peak accompanying melting.
The coefficient of thermal expansion of resin A is greater than that of resin No. 1. The coefficient of thermal expansion of the resin A may be, for example, 70/DEG C or more and 300/DEG C or less. The coefficient of thermal expansion of the resin a can be measured, for example, according to JIS K7197 "method for testing linear expansion coefficient based on thermal mechanical analysis of plastics".
The resin a may be contained in the second protective layer 2 as follows, for example. (1) The case where the 2 nd protective layer 12 is composed of the 2 nd conductive material and the resin a; (2) the 2 nd protective layer 12 contains a2 nd resin described later in addition to the 2 nd conductive material and the resin a; (3) the protective layer 10 includes a case of a3 rd protective layer described later.
In the case of the above (1), the content of the resin a with respect to the 2 nd protective layer 12 may be 45 mass% or more and 98 mass% or less, and preferably 50 mass% or more and 95 mass% or less.
In the case of (2) above, the content of the resin a with respect to the 2 nd protective layer 12 may be 0.05% by mass or more and 40% by mass or less, and preferably 0.1% by mass or more and 30% by mass or less.
In the case of (3) above, the content of the resin a with respect to the 2 nd protective layer 12 may be 0.05% by mass or more and 80% by mass or less, and preferably 0.1% by mass or more and 30% by mass or less.
(the 2 nd resin)
The 2 nd protective layer 12 may further include a2 nd resin. The 2 nd resin is a non-thermoplastic polyimide resin. The non-thermoplastic polyimide resin is not particularly limited as long as it is a polymer having an imide group in a repeating unit constituting the main chain and has a thermal decomposition temperature of at least 500 ℃. As the 2 nd resin, the same resin as the 1 st resin may be used.
No. 3 protective layer
Fig. 2 is a2 nd cross-sectional conceptual view showing a part of the structure of the positive electrode 100 of the present disclosure.
As shown in fig. 2, the protective layer 10 may further include a3 rd protective layer 13. The 3 rd protection layer 13 is disposed on the surface of the 2 nd protection layer 12. The positive electrode mixture layer 102 is disposed on the surface of the 3 rd protective layer 13. The 3 rd protective layer 13 includes the 1 st conductive material and the 1 st resin. As the 3 rd protective layer 13, there is no particular limitation as long as the 1 st conductive material and the 1 st resin are contained. The 3 rd protective layer 13 has the same composition and thickness as the 1 st protective layer. That is, the 1 st protective layer 11 may be disposed on the surface of the 2 nd protective layer 12 as the 3 rd protective layer 13. In the present specification, the phrase "the 3 rd protective layer 13 has the same composition as the 1 st protective layer 10" means: the composition contained in the 3 rd protective layer 13 is the same as the composition contained in the 1 st protective layer 10, or the difference from the composition contained in the 1 st protective layer 10 is 10 mass% or less. In addition, in the present specification, "the 3 rd protective layer 13 has the same thickness as the 1 st protective layer 10" means: the thickness of the 3 rd protective layer 13 is the same as that of the 1 st protective layer 10, or within 10% of that of the 1 st protective layer 10.
Negative electrode
Fig. 6 is a schematic diagram showing an example of the structure of the negative electrode of the present embodiment. The battery 1000 includes at least the negative electrode 200. The negative electrode 200 may be a strip-shaped sheet. The negative electrode 200 includes a negative electrode current collector 201 and a negative electrode mixture layer 202.
(negative electrode mixture layer)
The negative electrode mixture layer 202 is formed on the surface of the negative electrode current collector 201. The negative electrode mixture layers 202 may be formed on both front and back surfaces of the negative electrode current collector 201. The negative electrode mixture layer 202 may have a thickness of 80 μm or more and 250 μm or less, for example. The negative electrode mixture layer 202 contains at least a negative electrode active material. The negative electrode mixture layer 202 may contain, for example, 90 mass% to 99 mass% of a negative electrode active material and 1 mass% to 10 mass% of a binder.
The negative electrode active material electrochemically stores and releases charge carriers (lithium ions in the present embodiment). The negative electrode active material is not particularly limited. The negative electrode active material may be, for example, artificial graphite, natural graphite, soft carbon, hard carbon, silicon oxide, silicon-based alloy, tin oxide, tin-based alloy, or the like. 1 kind of negative electrode active material may be used alone. Two or more types of negative electrode active materials may be used in combination. The binder is also not particularly limited. The binder may be, for example, carboxymethyl cellulose (CMC), Styrene Butadiene Rubber (SBR), and the like. The negative electrode active material may have D50 of, for example, 1 μm or more and 30 μm or less.
(negative electrode collector)
The negative electrode current collector 201 is an electrode substrate having conductivity. The negative electrode current collector 201 may have a thickness of, for example, 5 μm or more and 50 μm or less, and preferably 7 μm or more and 12 μm or less. The negative electrode collector 201 may be, for example, a pure copper (Cu) foil, a Cu alloy foil, or the like.
Partition board
Fig. 4 is a schematic diagram showing an example of the structure of the electrode group 500 according to the present embodiment.
As shown in fig. 4, the battery 1000 may include a separator 300. The separator 300 is a strip-shaped film. The separator 300 is disposed between the positive electrode 100 and the negative electrode 200. The separator 300 may have a thickness of, for example, 5 μm or more and 30 μm or less, preferably 10 μm or more and 30 μm or less. The separator 300 is porous. The separator 300 electrically insulates the positive electrode 100 and the negative electrode 200. The separator 300 may be a porous film made of PE, PP, or the like, for example.
The separator 300 may have a single-layer structure, for example. The separator 300 may be formed of, for example, only a PE porous film. The separator 300 may have a multilayer structure, for example. The separator 300 can be formed by laminating a PP porous film, a PE porous film, and a PP porous film in this order. The separator 300 may include a heat-resistant layer on the surface thereof. The heat-resistant layer is a layer containing a heat-resistant material. The heat-resistant material may be, for example, alumina, polyimide, or the like.
Electrolyte solution
The battery 1000 may contain an electrolyte. The electrolyte contains at least a lithium (Li) salt and a solvent. The electrolyte solution may contain, for example, 0.5mol/l or more and 2mol/l or less of Li salt. The Li salt is a supporting electrolyte. The Li salt is dissolved in the solvent. The Li salt may be, for example, LiPF6、LiFSI、LiBF4、Li[N(FSO2)2]、Li[N(CF3SO2)2]And the like. 1 kind of Li salt can be used alone. Two or more Li salts may also be used in combination.
The solvent is aprotic. That is, the electrolytic solution of the present embodiment is a nonaqueous electrolyte. The solvent may be, for example, a mixture of cyclic carbonates and chain carbonates. The mixing ratio may be, for example, "cyclic carbonate: chain carbonate 1: 9-5: 5 (volume ratio) ".
The cyclic carbonate may be, for example, Ethylene Carbonate (EC), Propylene Carbonate (PC), Butylene Carbonate (BC), fluoroethylene carbonate (FEC), or the like. The cyclic carbonate 1 may be used alone. Two or more cyclic carbonates may be used in combination.
Examples of the chain carbonate include dimethyl carbonate (DMC), Ethyl Methyl Carbonate (EMC), and diethyl carbonate (DEC). 1 kind of chain carbonate may be used alone. Two or more kinds of chain carbonates may be used in combination.
The solvent may contain, for example, a lactone, a cyclic ether, a chain ether, a carboxylic acid ester, or the like. The lactone may be, for example, gamma-butyrolactone (GBL), delta-valerolactone, and the like. The cyclic ether may be, for example, Tetrahydrofuran (THF), 1, 3-dioxolane, 1, 4-dioxane, or the like. The chain ether may be 1, 2-Dimethoxyethane (DME) or the like. The carboxylic acid ester may be, for example, Methyl Formate (MF), Methyl Acetate (MA), Methyl Propionate (MP), or the like.
The electrolyte may contain various functional additives in addition to the Li salt and the solvent. The electrolyte solution may contain, for example, 1 mass% or more and 5 mass% or less of a functional additive. Examples of the functional additive include a gas generating agent (overcharge additive), and an sei (solid electrolyte interface) film forming agent. The gas generating agent may be, for example, Cyclohexylbenzene (CHB), Biphenyl (BP), or the like. The SEI film-forming agent may be, for example, Vinylene Carbonate (VC), Vinyl Ethylene Carbonate (VEC), Li [ B (C)2O4)2]、LiPO2F2Propane Sultone (PS), Ethylene Sulfite (ES), and the like.
< uses, etc. >
The battery 1000 of the present embodiment is expected to suppress an increase in battery temperature during nailing. Examples of applications that utilize this characteristic include a driving power source for a Hybrid Vehicle (HV), a plug-in hybrid vehicle (PHV), an Electric Vehicle (EV), and the like. However, the application of the battery 1000 of the present embodiment is not limited to the vehicle-mounted application. The battery 1000 of the present embodiment can be applied to all applications.
Examples
The following describes embodiments of the present disclosure. However, the following description does not limit the scope of the claims.
< example 1>
1. Formation of a protective layer
The following materials were prepared.
1 st conductive material: AB
Material of the 1 st resin: polyamic acid derived from pyromellitic acid dihydrate and 4, 4' -diaminodiphenyl ether
Conductive material No. 2: AB
Resin A: PVDF
Solvent: n-methyl-2-pyrrolidone (NMP)
Positive electrode current collector: al foil (thickness 15 μm)
(formation of the first protective layer)
The polyamic acid, AB as the 1 st conductive material, and NMP were mixed by a planetary mixer to prepare a slurry. In forming the 1 st protective layer 11, the slurry becomes a "polyimide resin (1 st resin): AB (1 st conductive material) ═ 99.5: 0.5'. The slurry was applied to the surface (front and back surfaces) of the positive electrode current collector 101 by a gravure coater (gravure coater), and dried. Then, a heat treatment was performed at 250 ℃ for 6 hours in nitrogen, thereby synthesizing a polyimide from the above polyamic acid. Thereby, the 1 st protective layer 11 is formed on the positive electrode current collector 101. The 1 st protective layer 11 (after drying, one side) had a thickness of 2 μm.
(formation of the second protective layer)
PVDF as the resin a, AB as the 2 nd conductive material, and NMP were mixed by a planetary mixer to prepare a slurry. The mixing ratio is "PVDF: AB 80: 20". The slurry was applied to the surface of the 1 st protective layer 11 disposed on the positive electrode current collector 101 by a gravure roll coater, and was dried. Then, it was cooled at 35 ℃ for 6 hours in nitrogen gas, thereby forming a2 nd protective layer 12 on the 1 st protective layer 11. The 2 nd protective layer 12 (after drying, one side) had a thickness of 2 μm. Through the above steps, the protective layer 10 composed of the 1 st protective layer 11 and the 2 nd protective layer 12 is formed on the positive electrode current collector 101.
2. Formation of positive electrode mixture layer
The following materials were prepared.
Positive electrode active material: LiNi0.82Co0.15Mn0.03O2(NCA)
Conductive material: AB
Adhesive: PVdF
Solvent: NMP
Positive electrode current collector: al foil having the protective layer 10 formed thereon
NCA, AB, PVdF and NMP were mixed using a planetary mixer. Thus, a slurry for a positive electrode mixture layer was prepared. The solid composition of the slurry for a positive electrode mixture layer was "NCA: AB: PVdF 88: 10: 2". The positive electrode mixture layer slurry was applied to the surface of the protective layer 10 by a comma coater (registered trademark), and dried. Thereby, the positive electrode mixture layer 102 is formed.
The positive electrode current collector 101, the protective layer 10, and the positive electrode mixture layer 102 are compressed by a rolling mill. Thereby preparing the positive electrode 100. The positive electrode mixture layer 102 (both surfaces) had a thickness of 150 μm.
3. Preparation of negative electrode
The following materials were prepared.
Negative electrode active material: amorphous carbon-coated graphite (Amorphous coated graphite) (particle diameter (D50): 25 μm)
Adhesive: SBR and CMC
Solvent: water (W)
Negative electrode current collector: cu foil (thickness 10 μm)
Amorphous carbon-coated graphite, SBR, CMC, and water were mixed by a planetary mixer. Thus, a slurry for a negative electrode mixture layer was prepared. The solid composition of the slurry for a negative electrode mixture layer was calculated in terms of mass ratio as "amorphous carbon-coated graphite: SBR: CMC 98: 1: 1". The slurry is applied to the surface (front and back surfaces) of the negative electrode current collector 201 and dried, thereby forming a negative electrode mixture layer 202.
The negative electrode mixture layer 202 and the negative electrode current collector 201 are compressed by a roll press. Thereby preparing the anode 200. The negative electrode mixture layer 202 (both surfaces) had a thickness of 160 μm.
4. Preparation of the separator
The following materials were prepared.
Heat-resistant material: boehmite (BO)
Adhesive: acrylic resin
Solvent: water (W)
And (3) isolation film: PE porous film (thickness 16 μm)
The boehmite, the acrylic resin and water were mixed to prepare a slurry. The slurry is applied to the surface of the separator 300 and dried, thereby forming a heat-resistant layer. The content of the acrylic resin in the heat-resistant layer was 4 mass%. The heat-resistant layer has a thickness of 5 μm. Thereby, the separator 300 is prepared.
5. Assembly
The positive electrode 100, the separator 300, the negative electrode plate 200, and the separator 300 are stacked in this order, and then wound in a spiral shape. Thereby forming an electrode group 500. The electrode group 500 is formed flat. The width dimension (dimension in the X-axis direction in fig. 3 and 4) of the electrode group 500 after molding was 130 mm. The height dimension (dimension in the Z-axis direction in fig. 3 and 4) of the electrode group 500 after molding was 50 mm. The terminals are connected to the electrode group 500. The electrode group 500 is housed in a battery case 1001.
An electrolyte having the following composition was prepared.
Solvent: [ EC: EMC: DMC 3: 3: 4]
Li salt: LiPF6(1.1mоl/l)
Additive: li [ B (C)2O4)2]And LiPO2F2
An electrolyte is injected into the battery case 1001. The battery case 1001 is sealed. Thus, the battery of example 1 was manufactured. The capacity ratio (negative electrode capacity/positive electrode capacity) was 1.9.
< examples 2 to 18>
As shown in table 1 below, a battery 1000 was produced in the same manner as in example 1, except that the kind of the 1 st conductive material, the content of the 1 st resin, the thickness of the 1 st protective layer 11, the kind of the 2 nd conductive material, the content of the resin a, and the thickness of the 2 nd protective layer 12 were changed.
< comparative example 1>
As shown in table 1 below, a battery 1000 was produced in the same manner as in example 1, except that the content of the 1 st conductive material, the content of the 1 st resin, and the thickness of the 1 st protective layer 11 were changed, and the 2 nd protective layer 12 was not formed.
< comparative example 2>
As shown in table 1 below, a battery 1000 was produced in the same manner as in example 1, except that the content of the 1 st conductive material, the content of the 1 st resin, and the thickness of the 1 st protective layer 11 were changed, the polyolefin was contained in the 1 st protective layer 11 in an amount of 20 mass%, and the 2 nd protective layer 12 was not formed.
< comparative example 3>
As shown in table 1 below, a battery 1000 was produced in the same manner as in example 1, except that the content of the 1 st conductive material, the content of the 1 st resin, and the thickness of the 1 st protective layer 11 were changed, the polyolefin was contained in the 1 st protective layer 11 in an amount of 20 mass%, and the content of the 2 nd conductive material, the kind of the resin a, the content of the resin a, and the thickness of the 2 nd protective layer 12 were changed.
< comparative example 4>
As shown in table 1 below, a battery 1000 was produced in the same manner as in example 1, except that the content of the 1 st conductive material, the content of the 1 st resin, the kind of the resin a, and the thickness of the 2 nd protective layer 12 were changed.
< examples 19 to 41>
As shown in table 2 below, a battery 1000 was produced in the same manner as in example 1, except that the kind of the 1 st conductive material, the content of the 1 st resin, the thickness of the 1 st protective layer 11, the kind of the 2 nd conductive material, the content of the resin a, and the thickness of the 2 nd protective layer 12 were changed, and a predetermined amount of the 2 nd resin was contained in the 2 nd protective layer 12. In example 41, the 2 nd protective layer 12 did not contain the 2 nd resin. In addition, as the 2 nd resin, the same resin as the 1 st resin was used.
< examples 42 to 64>
As shown in table 3 below, a battery 1000 was produced in the same manner as in example 1, except that the kind of the 1 st conductive material, the content of the 1 st resin, the thickness of the 1 st protective layer 11, the kind of the 2 nd conductive material, the content of the 2 nd conductive material, the kind of the resin a, the content of the resin a, and the thickness of the 2 nd protective layer 12 were changed, and the 2 nd protective layer 12 was made to contain a predetermined amount of the 2 nd resin, and the 3 rd protective layer 13 having the same composition and the same thickness as those of the 1 st protective layer 11 was disposed on the surface of the 2 nd protective layer 12. In example 64, the 2 nd protective layer 12 did not contain the 2 nd resin. In addition, as the 2 nd resin, the same resin as the 1 st resin was used.
< examples 65 to 72>
As shown in table 4 below, a battery 1000 was produced in the same manner as in example 1, except that the content of the 1 st conductive material, the content of the 1 st resin, the thickness of the 1 st protective layer 11, the kind of the resin a, the thickness of the 2 nd protective layer 12, and "β - α" (difference between the thermal decomposition temperature α of the 1 st resin and the melting point β of the positive electrode current collector 101) were changed.
< examples 73 to 88>
As shown in table 4 below, a battery 1000 was produced in the same manner as in example 1, except that the content of the 1 st conductive material, the content of the 1 st resin, the thickness of the 1 st protective layer 11, the content of the 2 nd conductive material, the type of the resin a, the content of the resin a, the thickness of the 2 nd protective layer 12, and "β — α" were changed, and a predetermined amount of the 2 nd resin was further contained in the 2 nd protective layer 12. The same resin as that of the 1 st resin was used as the 2 nd resin.
< evaluation >
1. High load charging and discharging
The following cycle "charge → rest (rest) → discharge" is 1 cycle, and 1000 cycles of charge and discharge are repeated.
Charging: 2.5 Cx 240 seconds
And (3) rest: 120 seconds
Discharging: 30X 20 seconds
Here, "1C" represents a current for discharging the full charge capacity in 1 hour. For example, "2.5C" means a current 2.5 times that of 1C.
The cell resistance was measured after 1 cycle and after 1000 cycles, respectively. The following formula is used: the resistance increase rate was calculated as [ battery resistance after 1000 cycles ]/[ battery resistance after 1 cycle ] × 100. The results are shown in the columns of "increase in resistance" in tables 1 to 4 below. The lower the rate of increase in resistance, the higher the resistance to high-load charge and discharge.
2. Nail penetration test
Staples (N staples, reference "N65") were prepared. The battery is fully charged. The cell was heated to 60 ℃. Nails (N nails, reference numeral "N65") having a trunk diameter of 3mm were prepared. The nail penetrates into the battery. The temperature of the battery case 1001 is monitored at a position 1cm from the position of nail penetration. The maximum reached temperature after the nail penetration was determined. The results are shown in the columns of "arrival temperature" in tables 1 to 4 below. The lower the maximum reached temperature, the more suppressed the increase in the battery temperature at the time of the nail penetration test.
3. Measurement of thermal decomposition temperature and melting Point
The thermal decomposition temperature of the polyimide used in the manufacture of the battery 1000 and the melting point of the resin a were measured by TG-DTA. The measurement conditions were: the temperature rise rate was 5 ℃/min and the Air (Air) flow rate was 200 mL/min. Thus, it was confirmed that the melting point of the resin a was lower than the thermal decomposition temperature of the polyimide. The results are shown in tables 1 to 4 under the columns "thermal decomposition temperature" and "melting point".
4. Determination of the coefficient of thermal expansion
The average thermal expansion coefficient of the polyimide and resin a used for the production of the battery 1000 was measured at room temperature (25 ℃) to 800 ℃ in a nitrogen gas flow atmosphere by a differential expansion method. Thus, it was confirmed that the thermal expansion coefficient of the resin a was larger than that of the polyimide. The results are shown in the columns of "expansion coefficients" in tables 1 to 4.
Figure GDA0003251459670000191
Figure GDA0003251459670000201
Figure GDA0003251459670000211
Figure GDA0003251459670000221
< results >
As shown in tables 1 to 4, examples 1 to 88 suppressed the increase in battery temperature at the time of nail penetration. The following phenomena (1) to (4) are considered to occur during the nailing. It is considered that the increase in the battery temperature at the time of the nail penetration is suppressed by the interaction of these phenomena.
(1) When the nail penetrates into the battery 1000, a short circuit occurs in a part of the battery 1000, and the temperature locally rises due to joule heat in the battery 1000.
(2) The expansion coefficient of the resin a contained in the 2 nd protective layer 12 is higher than that of the 1 st resin contained in the 1 st protective layer 11. Therefore, it is considered that the 2 nd protective layer 12 including the resin a expands to cover the 1 st protective layer 11 with an increase in temperature of the battery 1000. This prevents the 1 st protective layer 11 and the 2 nd protective layer 12 from being peeled off due to the nail penetration.
(3) The melting point of the resin a contained in the 2 nd protective layer 12 is lower than the thermal decomposition temperature of the 1 st resin contained in the 1 st protective layer 11. It is considered that the resin a melts and becomes liquid as the temperature of the battery 1000 increases. Therefore, when the void is generated in the 1 st resist layer 11, it is considered that the liquid resin a contained in the 2 nd resist layer 12 enters the void generated in the 1 st resist layer 11 and is welded. It is thus considered that the peeling of the 1 st protective layer 11 from the positive electrode current collector 101 due to the void and the exposure of the positive electrode current collector 101 are prevented.
(4) It is considered that the resin a melted into a liquid state adheres to the outer surface of the nail. This is considered to suppress a decrease in short-circuit resistance at the time of nail penetration and suppress an increase in battery temperature at the time of nail penetration.
1. Examination of Table 1
In comparative examples 1 and 2, the arrival temperature at the time of nailing was high. Since the 2 nd protective layer 12 is not provided, the 1 st protective layer 11 may be peeled off from the positive electrode current collector 101. Further, since the resin a is not contained, the molten resin a does not cover the nail, and the reduction of the short-circuit resistance at the time of nail penetration is not suppressed.
In comparative examples 3 and 4, the arrival temperature at the time of nailing was high. Although these examples have the 2 nd protective layer 12, the polyimide (comparative example 3) and the polyamideimide (comparative example 4) used as the resin a do not correspond to the thermoplastic resin, and the expansion coefficient is small. It is therefore considered that the 2 nd protective layer 12 containing the resin a does not sufficiently swell in such a manner as to cover the 1 st protective layer 11. Further, it is considered that the resin a (polyimide, and polyamideimide) does not sufficiently adhere to the outer surface of the nail.
Examples 1 to 12 suppress an increase in battery temperature at the time of nail penetration and an increase in battery resistance at the time of high-load charge and discharge. Namely, it was shown that: in the case where the 2 nd protective layer is composed of the 2 nd conductive material and the resin a, the following (a1) to (a4) are preferably satisfied.
(a1) The content of the 1 st conductive material with respect to the 1 st protective layer 11 is 0.5 mass% or more and 50 mass% or less.
(a2) The content of the 2 nd conductive material with respect to the 2 nd protective layer 12 is 5 mass% or more and 50 mass% or less.
(a3) The content of the resin a with respect to the 2 nd protective layer 12 is 50 mass% or more and 95 mass% or less.
(a4) The 1 st protective layer 11 and the 2 nd protective layer 12 each have a thickness of 0.1 μm or more and 10 μm or less.
2. Examination of Table 2
In examples 19 to 41, the increase in the battery temperature at the time of nail penetration was suppressed. Namely, it was shown that: the 2 nd protective layer 12 may contain a2 nd resin which is a non-thermoplastic polyimide resin in addition to the resin a.
Examples 19 to 33 suppressed the increase in battery temperature at the time of nail penetration, and also suppressed the increase in battery resistance at the time of high-load charge and discharge. Namely, it was shown that: in the case where the 2 nd protective layer contains the 2 nd conductive material, the resin a, and the 2 nd resin, the following (b1) to (b4) are preferably satisfied.
(b1) The content of the 1 st conductive material with respect to the 1 st protective layer 11 is 0.5 mass% or more and 50 mass% or less.
(b2) The content of the 2 nd conductive material with respect to the 2 nd protective layer 12 is 0.5 mass% or more and 50 mass% or less.
(b3) The content of the resin a in the 2 nd protective layer 12 is 0.1 mass% or more and 30 mass% or less.
(b4) The 1 st protective layer 11 and the 2 nd protective layer 12 each have a thickness of 0.1 μm or more and 10 μm or less.
3. Examination of Table 3
In examples 42 to 64, the increase in the battery temperature at the time of nail penetration was suppressed. Thus, it is shown that the protective layer 10 may further include a3 rd protective layer 13 on the surface of the 2 nd protective layer 12. In examples 42 to 64, the 3 rd protective layer 13 had the same composition and thickness as the 1 st protective layer 11.
Examples 42 to 56 suppressed the increase in battery temperature at the time of nail penetration, and also suppressed the increase in battery resistance at the time of high-load charge and discharge. Namely, it was shown that: when the 2 nd protective layer 12 includes the 2 nd conductive material, the resin a, and the 2 nd resin, and the 3 rd protective layer 13 is formed on the 2 nd protective layer 12, the following (c1) to (c4) are preferably satisfied.
(c1) The content of the 1 st conductive material with respect to the 1 st protective layer 11 is 0.5 mass% or more and 50 mass% or less.
(c2) The content of the 2 nd conductive material with respect to the 2 nd protective layer 12 is 0.5 mass% or more and 50 mass% or less.
(c3) The content of the resin a in the 2 nd protective layer 12 is 0.1 mass% or more and 30 mass% or less.
(c4) The 1 st protective layer 11 and the 2 nd protective layer 12 each have a thickness of 0.1 μm or more and 10 μm or less.
4. Examination of Table 4
Examples 65 to 88 suppressed the increase in battery temperature at the time of nail penetration, and also suppressed the increase in battery resistance at the time of high-load charge and discharge. This shows that: the resin a is preferably at least 1 selected from PVDF, polyethylene, polycarbonate, silicone rubber, polyethylene terephthalate, fluororubber, and PTFE.
In examples 66 to 68, 74 to 76, and 82 to 84, the increase in the battery temperature at the time of nail penetration was significantly suppressed. Namely, it was shown that: the difference (β - α) between the thermal decomposition temperature α of the 1 st resin and the melting point β of the positive electrode current collector 101 is preferably 120 ℃ or less. In examples 66 to 68, 74 to 76, and 82 to 84, since the difference (β - α) between the thermal decomposition temperature α of the 1 st resin and the melting point β of the positive electrode current collector 101 was 120 ℃ or less, it is considered that the time from the start of thermal decomposition of the 1 st resin to the fusing of the positive electrode current collector 101 was shortened. This shortens the time for exposing the positive electrode current collector 101, and reduces the frequency of the positive electrode current collector 101 contacting the nail.
The embodiments of the present invention have been described, but the embodiments disclosed herein are not intended to be limiting in all respects. The scope of the present invention is defined by the appended claims, and all changes that come within the meaning and range of equivalency of the claims are intended to be embraced therein.

Claims (14)

1. A nonaqueous electrolyte secondary battery comprising at least a positive electrode, a negative electrode, a separator and a nonaqueous electrolyte,
the positive electrode comprises a positive electrode current collector, a protective layer and a positive electrode mixture layer,
the protective layer is disposed between the positive electrode current collector and the positive electrode mixture layer,
the protective layer comprises at least a1 st protective layer and a2 nd protective layer,
the 1 st protective layer is disposed on the surface of the positive electrode current collector,
the 1 st protective layer includes a1 st conductive material and a1 st resin,
the 1 st resin is a non-thermoplastic polyimide resin,
the 2 nd protective layer is configured on the surface of the 1 st protective layer,
the 2 nd protective layer contains at least a2 nd conductive material and a resin a,
the resin a is a thermoplastic resin and,
the melting point of the resin A is lower than the thermal decomposition temperature of the 1 st resin,
the expansion coefficient of the resin A is larger than that of the 1 st resin.
2. The nonaqueous electrolyte secondary battery according to claim 1,
the resin A is at least 1 selected from the group consisting of polyvinylidene fluoride (PVDF), polyethylene, polycarbonate, silicone rubber, polyethylene terephthalate (PET), fluororubber, and Polytetrafluoroethylene (PTFE).
3. The nonaqueous electrolyte secondary battery according to claim 1 or 2,
the 2 nd protective layer further comprises a2 nd resin,
the 2 nd resin is a non-thermoplastic polyimide resin.
4. The nonaqueous electrolyte secondary battery according to claim 1 or 2,
the protective layer further comprises a3 rd protective layer,
the 3 rd protective layer is configured on the surface of the 2 nd protective layer,
the 3 rd protective layer has the same composition and thickness as the 1 st protective layer.
5. The nonaqueous electrolyte secondary battery according to claim 1 or 2,
the content of the 1 st conductive material relative to the 1 st protective layer is 0.5 mass% or more and 50 mass% or less,
the content of the 2 nd conductive material with respect to the 2 nd protective layer is 5 mass% or more and 50 mass% or less,
the content of the resin A relative to the 2 nd protective layer is 50-95 mass%,
the 1 st protective layer and the 2 nd protective layer each have a thickness of 0.1 μm or more and 10 μm or less.
6. The nonaqueous electrolyte secondary battery according to claim 1 or 2,
the difference beta-alpha between the thermal decomposition temperature alpha of the 1 st resin and the melting point beta of the positive electrode current collector is 120 ℃ or less.
7. The nonaqueous electrolyte secondary battery according to claim 3,
the content of the 1 st conductive material relative to the 1 st protective layer is 0.5 mass% or more and 50 mass% or less,
the content of the 2 nd conductive material relative to the 2 nd protective layer is 0.5 mass% or more and 50 mass% or less,
the content of the resin A relative to the 2 nd protective layer is more than or equal to 0.1 mass% and less than or equal to 30 mass%,
the 1 st protective layer and the 2 nd protective layer each have a thickness of 0.1 μm or more and 10 μm or less.
8. The nonaqueous electrolyte secondary battery according to claim 3,
the protective layer further comprises a3 rd protective layer,
the 3 rd protective layer is configured on the surface of the 2 nd protective layer,
the 3 rd protective layer has the same composition and thickness as the 1 st protective layer.
9. The nonaqueous electrolyte secondary battery according to claim 4,
the content of the 1 st conductive material relative to the 1 st protective layer is 0.5 mass% or more and 50 mass% or less,
the content of the 2 nd conductive material relative to the 2 nd protective layer is 0.5 mass% or more and 50 mass% or less,
the content of the resin A relative to the 2 nd protective layer is more than or equal to 0.1 mass% and less than or equal to 30 mass%,
the 1 st protective layer and the 2 nd protective layer each have a thickness of 0.1 μm or more and 10 μm or less.
10. The nonaqueous electrolyte secondary battery according to claim 8,
the content of the 1 st conductive material relative to the 1 st protective layer is 0.5 mass% or more and 50 mass% or less,
the content of the 2 nd conductive material relative to the 2 nd protective layer is 0.5 mass% or more and 50 mass% or less,
the content of the resin A relative to the 2 nd protective layer is more than or equal to 0.1 mass% and less than or equal to 30 mass%,
the 1 st protective layer and the 2 nd protective layer each have a thickness of 0.1 μm or more and 10 μm or less.
11. The nonaqueous electrolyte secondary battery according to claim 3,
the difference beta-alpha between the thermal decomposition temperature alpha of the 1 st resin and the melting point beta of the positive electrode current collector is 120 ℃ or less.
12. The nonaqueous electrolyte secondary battery according to claim 4,
the difference beta-alpha between the thermal decomposition temperature alpha of the 1 st resin and the melting point beta of the positive electrode current collector is 120 ℃ or less.
13. The nonaqueous electrolyte secondary battery according to claim 5,
the difference beta-alpha between the thermal decomposition temperature alpha of the 1 st resin and the melting point beta of the positive electrode current collector is 120 ℃ or less.
14. The nonaqueous electrolyte secondary battery according to any one of claims 7 to 10,
the difference beta-alpha between the thermal decomposition temperature alpha of the 1 st resin and the melting point beta of the positive electrode current collector is 120 ℃ or less.
CN201910054594.7A 2018-01-22 2019-01-21 Nonaqueous electrolyte secondary battery Active CN110071260B (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2018008310A JP6933149B2 (en) 2018-01-22 2018-01-22 Non-aqueous electrolyte secondary battery
JP2018-008310 2018-01-22

Publications (2)

Publication Number Publication Date
CN110071260A CN110071260A (en) 2019-07-30
CN110071260B true CN110071260B (en) 2021-12-24

Family

ID=67298782

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201910054594.7A Active CN110071260B (en) 2018-01-22 2019-01-21 Nonaqueous electrolyte secondary battery

Country Status (3)

Country Link
US (1) US10903515B2 (en)
JP (1) JP6933149B2 (en)
CN (1) CN110071260B (en)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114551855A (en) * 2020-11-24 2022-05-27 通用汽车环球科技运作有限责任公司 Electrode and electrochemical cell comprising a dendrite inhibitor protective coating
CN112701249A (en) * 2021-01-04 2021-04-23 昆山宝创新能源科技有限公司 Positive plate and preparation method and application thereof
CN113078282A (en) * 2021-03-23 2021-07-06 珠海冠宇电池股份有限公司 Positive plate and lithium ion battery
US20230402601A1 (en) 2022-06-08 2023-12-14 Semiconductor Energy Laboratory Co., Ltd. Battery
DE102023119314A1 (en) 2022-07-29 2024-02-01 Semiconductor Energy Laboratory Co., Ltd. Secondary battery

Family Cites Families (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3311402B2 (en) * 1992-11-19 2002-08-05 三洋電機株式会社 Rechargeable battery
JP4567822B2 (en) 1999-03-24 2010-10-20 株式会社東芝 Square non-aqueous electrolyte secondary battery
WO2009054987A1 (en) * 2007-10-26 2009-04-30 Sion Power Corporation Primer for battery electrode
WO2011037124A1 (en) * 2009-09-25 2011-03-31 ダイキン工業株式会社 Positive electrode current collector laminate for lithium secondary battery
BR112012012049B1 (en) * 2009-11-20 2021-11-23 Nissan Motor Co., Ltd CURRENT COLLECTOR FOR BIPOLAR SECONDARY BATTERY, ELECTRODE FOR BIPOLAR SECONDARY BATTERY AND BIPOLAR SECONDARY BATTERY
JP5055350B2 (en) 2009-12-28 2012-10-24 シャープ株式会社 Nonaqueous electrolyte secondary battery and electrode for nonaqueous electrolyte secondary battery
CN102959768B (en) 2010-07-06 2015-04-01 株式会社杰士汤浅国际 Electrode body for energy storage element, and energy storage element
JP5770553B2 (en) * 2011-07-26 2015-08-26 日産自動車株式会社 Bipolar lithium-ion secondary battery current collector
JP6015222B2 (en) * 2012-08-09 2016-10-26 大日本印刷株式会社 Negative electrode plate for secondary battery, secondary battery, and battery pack
JP2015069881A (en) * 2013-09-30 2015-04-13 凸版印刷株式会社 Electrode and battery arranged by use thereof
KR101709569B1 (en) * 2014-12-16 2017-02-23 주식회사 엘지화학 Manufacturing Method for Electrode for Secondary Battery Including PTC Material and Electrode Manufactured by the Same

Also Published As

Publication number Publication date
US10903515B2 (en) 2021-01-26
JP2019129009A (en) 2019-08-01
US20190229367A1 (en) 2019-07-25
JP6933149B2 (en) 2021-09-08
CN110071260A (en) 2019-07-30

Similar Documents

Publication Publication Date Title
CN110071260B (en) Nonaqueous electrolyte secondary battery
US10186700B2 (en) Heat-resistant microporous film and battery separator
WO2017094712A1 (en) Lithium ion secondary battery
WO2010007720A1 (en) Battery pack
US11316205B2 (en) Lithium ion secondary battery and method of manufacturing the same
CN109494355B (en) Negative electrode, lithium ion secondary battery, method for producing negative electrode, and method for producing lithium ion secondary battery
CN109698316B (en) Nonaqueous electrolyte secondary battery
KR20090050001A (en) Non-aqueous electrolyte battery
JP2007273183A (en) Negative electrode and secondary battery
CN109155426B (en) Lithium ion secondary battery
JP5005935B2 (en) Nonaqueous electrolyte secondary battery
CN110323414B (en) Nonaqueous electrolyte secondary battery and method for manufacturing nonaqueous electrolyte secondary battery
WO2016194733A1 (en) Lithium ion secondary battery
JP2019216061A (en) Lithium ion battery electrode and lithium ion battery
CN110021781B (en) Non-aqueous electrolyte secondary battery
JP2019079708A (en) Positive electrode and non-aqueous electrolyte secondary battery including the same
JP5207282B2 (en) Lithium secondary battery
CN109686907B (en) Separator, nonaqueous electrolyte secondary battery, and method for producing separator
CN108695517B (en) Battery with a battery cell
JP5582573B2 (en) Secondary battery and electrolyte for secondary battery used therefor
JP2018174064A (en) Nonaqueous electrolyte secondary battery
CN108736015B (en) Nonaqueous battery
WO2020071469A1 (en) Electrolyte solution for lithium ion secondary batteries, and lithium ion secondary battery
EP3869586A1 (en) Negative electrode for lithium ion secondary battery, and lithium ion secondary battery
KR20050013717A (en) Electrolyte for lithium secondary cell having excellent performance at low temperature and lithium secondary cell comprising its electrolyte

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant